The present invention relates generally to the control of aquatic plants, and in particular to supported fluridone compositions useful for the control of aquatic plants.
The compound 1-methyl-3-phenyl-5-3-(trifluoromethyl)-phenyl-4(1H)-pyridinone, commonly known as fluridone, has proven to be a highly effective aquatic herbicide for controlling a wide range of undesirable aquatic plants. To date, fluridone has been commercially available in both liquid and solid (pellet) formulations. Commercial pellet-form fluridone compositions have utilized a carrier comprised of kaolin clay, which has provided a slow release of fluridone over an extended period of time. This has facilitated the maintenance of low levels of fluridone in treated water bodies for extended periods of time.
The use of aquatic herbicides such as fluridone has become a common method for controlling invasive aquatic weeds. However, the use of such herbicidal control presents risks and difficulties including the potential impact on the local environment, variations in conditions of treatment caused by water flow and other factors, and the potential for differential herbicide-tolerance to develop. For these reasons, it is important that any fluridone formulation used provides an optimal treatment regimen.
In light of this background, there is a need for improved fluridone compositions useful for the control of aquatic plants. Such compositions will desirably facilitate the ability to maintain lethal threshold concentrations of fluridone so as to avoid situations in which insufficient levels of fluridone are present thus resulting in treatment failure as well as increasing the chances of the plant becoming more tolerant. The present invention addresses these needs.
It has been discovered that advantageous fluridone compositions can be prepared having a relatively quick initial release of fluridone while also maintaining an advantageous extended fluridone release. Such compositions can be prepared, for example, by supporting fluridone on a solid carrier comprising a suitable hormite mineralogy such as an attapulgite type mineralogy, or on a solid carrier comprising a suitable bentonite mineralogy or another substantially swellable clay mineralogy exhibiting similar release characteristics. The fluridone can be loaded on the carrier, for example, to provide a composition comprised about 1% to about 20% by weight fluridone. Preferred fluridone compositions are solid, formed articles such as pellets, tablets or granules, and are effective to release at least 20% of their fluridone load within about 10 days after immersion in static, distilled water. Still further preferences exist where the composition is comprised about 1% to about 10% by weight of fluridone, more preferably about 3% to 7% by weight fluridone. The solid carrier is desirably at least 20% by weight comprised of attapulgite type mineralogy.
In another embodiment, the present invention provides a method of controlling aquatic plants which comprises introducing into a body of water containing the plants an effective amount of a fluridone composition of the invention.
In still another embodiment, the present invention provides a method for manufacturing a fluridone composition which comprises supporting fluridone on a solid carrier containing attapulgite type mineralogy.
The present invention provides fluridone compositions having advantageous fluridone release profiles and which are effective for the control of aquatic plants. The invention also provides methods of making and using such compositions. These and additional embodiments, as well as advantages and features of the invention will be apparent from the descriptions herein.